TIJUANA, Mexico - A group of gunmen who shot their way into a public hospital Wednesday, killing two police officers and creating panic among staff and patients, were members of the Arellano Felix drug cartel, the region's major drug trafficking group, a federal official said Thursday.

The assailants were trying to reach a fellow cartel member, Javier Estrada Dominguez, who was being treated at Tijuana's General Hospital after a shootout with police, said Patricio Patino Arias, a top official with Mexico's Public Safety Secretariat.

Four people tried to rescue the wounded man, Patino said.

One of the four, Ernesto Sanchez Vega, 23, was captured. He told police a man identified only as "El Verde" had ordered them to retrieve Estrada.

Patino identified Sanchez's accomplices only by their nicknames: "El Bloque," "El Macaco" and "La Roca." The three apparently escaped, although Patino did not explicitly say that.

Patino's statements at a news conference in Mexico City on Thursday provided the most extensive description so far of the shootings that led to partial evacuation of the hospital and brought hundreds of police officers and military personnel to the area. But many details remained unclear, and some of Patino's statements contradict previous information offered by Baja California authorities.

He said police who started the pursuit were acting on leads that an armed group was planning an attack on drug traffickers. Patino didn't say who had been planning the attack, but he said it was aimed at the "Milenio Cartel."

The Milenio group, Patino said, is led by drug trafficking suspect Joaquin Guzman and includes heavyweights such as trafficking suspect Ismael Zambada. The group has been trying to move into the Arellanos' turf in recent years.

The law enforcement agents' intelligence led them to focus on a white pickup in a neighborhood behind the city's main bus station. When the driver refused to stop, a shootout ensued. After the truck crashed into a bus, the driver and passenger ran away.

One man died at the scene. Estrada was wounded, and an ambulance took him to the General Hospital. Doctors operated on him Wednesday for two gunshot wounds and turned him over to federal authorities Thursday, state health officials said.

The Arellanos have suffered a series of setbacks in recent years, including the arrests of their top leaders, leading some to contemplate the cartel's demise. "In the city of Tijuana, the Arellano Felix cartel continues operating," Patino said.

At the hospital Thursday, workers were patching up damaged sections of the emergency unit, where glass had shattered and a bullet pierced a water pipe, but the rest of the hospital was operating normally. Authorities expected to reopen the unit Friday.